Flame retartdant epoxy resins comprising phosphorus containing flame retardants

1. A process for preparing electrical laminates comprising:

formulating a flame retardant epoxy composition comprising:

a) an epoxy resin,

b) from 1% to 60%, by weight based on the total weight of the flame retardant epoxy composition, of a flame retardant material obtained by a process comprising heating at temperatures of about 200° C. or higher from about 0.01 hour to about 20 hours one or more than one compound of formula (I)

wherein

R is C 1-12 alkyl, C 6-10 aryl, C 7-18 alkylaryl, or C 7-18 arylalkyl, wherein said alkyl, aryl, alkylaryl, or arylalkyl are unsubstituted or are substituted by halogen, hydroxyl, amino, C 1-4 alkylamino, di-C 1-4 alkylamino, C 1-4 alkoxy, carboxy or C 2-5 alkoxycarbonyl;

M is a metal,

y is a number of from 1 to 4 so that M (+)y is a metal cation where (+)y represents the charge formally assigned to the cation, and p is a number of from 1 to 4, and

c) a curing agent;

applying to, or impregnating into a substrate said flame retardant epoxy composition to obtain an epoxy coated substrate,

heating the epoxy coated substrate at a temperature sufficient to draw off solvent from the flame retardant epoxy composition and optionally to partially cure the flame retardant epoxy composition to form a prepreg, followed by

stacking sheets of prepreg or layering sheets of prepreg, in alternating layers, with one or more sheets of a conductive material followed by processing to provide fully processed laminates.

2. The process according to claim 1 wherein the flame retardant material (b) is obtained by a process comprising:

i) preparing an intermediate salt complex by treating one or more phosphonic acid compound with one or more appropriate metal compound to give an intermediate salt complex corresponding to formula (I) comprising multiple values for R and/or M, and then heating the intermediate salt complex at temperatures of about 200° C. or higher for about 0.01 hour to about 20 hours;

or

ii) preparing an intimate salt mixture by combining two or more individual metal phosphonic acid salts of formula (I) which have differing values for R and/or M, and then heating the intimate salt mixture at temperatures of about 200° C. or higher for about 0.01 hour to about 20 hours;

or

(iii) heating at temperatures of about 200° C. or higher for about 0.01 hour to about 20 hours two or more separate metal phosphonic acid salts of formula (I), which differ by having different values for R and/or M to form individual flame retardant materials that are subsequently mixed together to form a blended flame retardant material.

3. The process according to claim 1 wherein M in formula (I) is Li, K, Na, Mg, Ca, Ba, Zn, Zr, B, Al, Si, Ti, Sn or Sb.

4. The process according to claim 1 wherein M in formula (I) is Al or Ca.

5. The process according to claim 1 wherein in formula (I) R is unsubstituted C 1-6 alkyl, C 6 aryl, C 7-10 alkylaryl, or C 7-12 arylalkyl.

6. The process according to claim 1 wherein the flame retardant epoxy composition further comprises d) one or more compounds selected from the group consisting of additional flame retardants, one or more synergists and flame retardant adjuvants.

7. The process according to claim 1 wherein the curing agent comprises a phenolic cross linker, a diamine, a polyamine, a dicyandiamide or a substituted dicyandiamide.

8. The process according to claim 1 wherein the epoxy resin comprises an epoxy novolac resin and/or a novolac cross linker.

9. The process according to claim 1 wherein the flame retardant epoxy resin composition further comprises one or more additional resins selected from the group consisting of cyanate resins, bismaleimide resins, polyimide resins, phenolic resins, furan resins, xylene formaldehyde resins, ketone formaldehyde resins, urea resins, melamine resins, aniline resins, alkyd resins, unsaturated polyester resins, diallyl phthalate resins, triallyl cyanate resins, triazine resins, polyurethane resins, polyolefin resins, polyphenylene ether resins, benzocyclobutene resins, benzoxazine resins and silicone resins.

10. An electrical laminate obtained according to the process according to claim 1 .

11. A process for preparing a prepreg useful in manufacturing a laminate comprising:

formulating a flame retardant epoxy composition comprising:

a) an epoxy resin,

b) from 1% to 60%, by weight based on the total weight of the flame retardant epoxy composition, of a flame retardant material obtained by a process comprising heating at temperatures of about 200° C. or higher from about 0.01 hour to about 20 hours one or more than one compound of formula (I)

wherein

R is C 1-12 alkyl, C 6-10 aryl, C 7-18 alkylaryl, or C 7-18 arylalkyl, wherein said alkyl, aryl, alkylaryl, or arylalkyl are unsubstituted or are substituted by halogen, hydroxyl, amino, C 1-4 alkylamino, di-C 1-4 alkylamino, C 1-4 alkoxy, carboxy or C 2-5 alkoxycarbonyl;

M is a metal,

y is a number of from 1 to 4 so that M (+)y is a metal cation where (+)y represents the charge formally assigned to the cation, and p is a number of from 1 to 4, and

c) a curing agent;

applying to, or impregnating into a substrate said flame retardant epoxy composition to obtain an epoxy coated substrate,

heating the epoxy coated substrate at a temperature sufficient to draw off solvent from the flame retardant epoxy composition and optionally to partially cure the flame retardant epoxy composition to form a prepreg.

12. The process according to claim 11 wherein the flame retardant material (b) is obtained by a process comprising:

i) preparing an intermediate salt complex by treating one or more phosphonic acid compound with one or more appropriate metal compound to give an intermediate salt complex corresponding to formula (I) comprising multiple values for R and/or M, and then heating the intermediate salt complex at temperatures of about 200° C. or higher for about 0.01 hour to about 20 hours;

or

ii) preparing an intimate salt mixture by combining two or more individual metal phosphonic acid salts of formula (I) which have differing values for R and/or M, and then heating the intimate salt mixture at temperatures of about 200° C. or higher for about 0.01 hour to about 20 hours;

or

(iii) heating at temperatures of about 200° C. or higher for about 0.01 hour to about 20 hours two or more separate metal phosphonic acid salts of formula (I), which differ by having different values for R and/or M to form individual flame retardant materials that are subsequently mixed together to form a blended flame retardant material.

13. The process according to claim 11 wherein M in formula (I) is Li, K, Na, Mg, Ca, Ba, Zn, Zr, B, Al, Si, Ti, Sn or Sb.

14. The process according to claim 11 wherein M in formula (I) is Al or Ca.

15. The process according to claim 11 wherein in formula (I) R is unsubstituted C 1-6 alkyl, C 6 aryl, C 7-10 alkylaryl, or C 7-12 arylalkyl.

16. The process according to claim 11 wherein the flame retardant epoxy composition further comprises d) one or more compounds selected from the group consisting of additional flame retardants, one or more synergists and flame retardant adjuvants.

17. The process according to claim 11 wherein the curing agent comprises a phenolic cross linker, a diamine, a polyamine, a dicyandiamide or a substituted dicyandiamide.

18. The process according to claim 11 wherein the epoxy resin comprises an epoxy novolac resin and/or a novolac cross linker.

19. The process according to claim 11 wherein the flame retardant epoxy resin composition further comprises one or more additional resins selected from the group consisting of cyanate resins, bismaleimide resins, polyimide resins, phenolic resins, furan resins, xylene formaldehyde resins, ketone formaldehyde resins, urea resins, melamine resins, aniline resins, alkyd resins, unsaturated polyester resins, diallyl phthalate resins, triallyl cyanate resins, triazine resins, polyurethane resins, polyolefin resins, polyphenylene ether resins, benzocyclobutene resins, benzoxazine resins and silicone resins.

20. A prepreg obtained according to the process according to claim 11 .